The invention relates to a catheter for aspirating, fragmenting and removing extractable material from hollow bodies, in particular thrombi and emboli from blood vessels, with a working head, which is arranged at the distal end of the catheter, is axially displaceable along a guide wire, independently thereof, and comprises at least one lateral opening, the catheter comprising a flexible feed screw which has a distal part and a proximal part and which can be rotated at a speed of rotation by means of a rotary drive of a drive unit remote from the working head, and with a flexible tube which surrounds the feed screw and is connected to the working head to remove the material or the detached thrombi and emboli fragments, and with a cutting tool, the feed screw being designed as a shearing cutting tool which cooperates with the opening in the working head in order to size-reduce the materials or aspirated and/or detached thrombi and emboli which penetrate between the peripheral edges of the feed screw and edges of the openings.
WO 2005/084562 A2, in the name of the applicant, discloses catheters which are used in particular to remove fresh blood clots from blood vessels in order to prevent these clots from blocking narrow regions and obstructing the blood vessels (‘embolisms’). The content of WO 2005/084562 A2, in particular in terms of the embodiments disclosed therein of openings in the working head of the catheter, is hereby included in full scope as a component of the present application (FIGS. 6-10: rectangular lateral opening; FIGS. 11-15, claim 10: working head with a narrow slit extending in the longitudinal direction of the working head; FIGS. 16-20: approximately square lateral opening; FIGS. 21-25, claim 11: slitted opening extending in the peripheral direction of the working head; FIGS. 26-30, claims 15-17: grooved recess proceeding from the distal end of the working head and opening out into the lateral opening; FIGS. 31-35: working head with a lateral opening formed as an elongate slit and a grooved recess proceeding from the distal end of the working head and opening out into the lateral opening; FIGS. 36-40: approximately triangular lateral opening, of which the width narrows towards the proximal end; FIGS. 41-60 and claims 3, 4 and 14: lateral opening which consists of a region extending in the axial direction and a region extending over a part of the periphery of the working head, again having different embodiments of the partial regions of the opening in accordance with the description of the figures on page 11; FIGS. 61-65: opening extending along a screw line of the feed screw; FIGS. 66-80: opening extending along a screw line of the feed screw and which opens out into a region of the opening extending in the axial direction).
WO 96/29941 A1 discloses a rotary catheter for atherectomy, of which the working head consists of a stationary stator connected to a tube and a rotor. The rotor is rotatable relative to the stator by means of a high-speed feed/drive screw. Both the stator and the rotor have apertures over their periphery which can be aligned. The parts protruding or aspirated into the openings are size-reduced by shearing between a blade on the rotor and a counter-blade on the openings in the stator. The rotor can surround the stator externally (‘external rotor’) or may be arranged inside the rotor (Internal rotor'). This rotary catheter is used, above all, where relatively hard and rather brittle coatings have formed over time on the inner wall of blood vessels, such as veins and the like. However, the design according to WO 2005/084562 A2 is better adapted for the removal of fresh blood clots (such as thrombi) from blood vessels.
The content of WO 96/29941 A1, in particular in terms of the embodiments disclosed therein of openings in the stator and rotor, is hereby also included in full scope as a component of the present application (FIGS. 2, 3, 6, 7, 9, 10 and 12 with substantially oval through-openings in the stator and in the rotor, in conjunction with the corresponding parts of the description: p. 5, lines 23-24 and p. 8, lines 14-33 with reference to FIG. 2; p. 5, line 26 and p. 9, lines 1-17 with reference to FIG. 3; p. 6, lines 2-4 and p. 10, lines 24-28 with reference to FIG. 6; p. 6, lines 6-7 and p. 10, line 30 to p. 11, line 3 with reference to FIG. 7; p. 6, lines 12-14 and pages 15-16 with reference to FIG. 9; p. 6, lines 16-18 and p. 11, lines 15-16 with reference to FIG. 10; p. 6, lines 23-24 and p. 11, line 18 to p. 12, line 28 with reference to FIG. 12).
The blood clots to be removed are often very fibrous and tough and can only be removed in part with effort and at high cost in terms of time and equipment, or else cannot be removed at all. Sometimes the obstructing material blocks the threads of the feed screw, so hardly any more material can be conveyed. If the feed screw becomes blocked then it may become damaged and the catheter thus becomes useless.
U.S. Pat. No. 5,569,178 A discloses a catheter in which the distal end of the feed screw is mounted in a thrust bearing which is provided in a corresponding recess.